Apparatus for testing items of metal such as jewelry

ABSTRACT

Apparatus (1) for testing items of metal such as jewelry comprises a housing (3) which is closed at one end (3a) and partly open at the other end (3b). Sealed within the housing is an insert comprising a reservoir (5) containing a testing chemical and an applicator (7). The applicator extends into the reservoir (5) and projects from the housing through its partly open end (3b). The outer surface of the applicator (7) projecting from the housing forms a tip which is used to apply the testing chemical to the surface of the metal under test.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to apparatus for testing items of metalsuch as jewellery.

2. Brief Discussion of the Related Art

It is known to test items of jewellery or the like with chemicals todetermine whether or not they are made of a precious metal or metalalloy and, if so, the grade of such metal. Such chemicals are providedin an "acid set" comprising a set of glass bottles containing differenttesting chemicals, each bottle having a glass rod or spatula forapplying the chemical to the item to be tested. By observing thereaction (or lack of reaction) of the item under test with one or moreof the testing chemicals, it is possible to determine whether or not theitem contains or comprises metals such as gold, silver, platinum,palladium, copper, or certain other base metals or their alloys.

GB-A-2 124 367 discloses such a known method of testing precious metals.

SUMMARY OF THE INVENTION

The present invention provides apparatus for testing items of metalcomprising a reservoir for testing chemical, an applicator fortransferring testing chemical from the reservoir to an applying surfacethereof and a housing surrounding the reservoir and applicator with theapplying surface projecting therefrom. The apparatus is characterised inthat the reservoir comprises an absorbent material and the applicatorcomprises a nib having a wick in contact with testing chemical withinthe reservoir, and a tip which forms the applying surface.

Preferably the absorbent material of the reservoir is a porous plasticmaterial, such as a fibrous or granular plastics material, preferablycomprising polypropylene fibres. The reservoir may be sealed within afilm or tube which is resistant to the testing chemical. The nib maycomprise any suitable material which will not be deteriorated by thetesting chemical. Very preferably the nib is formed of a granular orfibrous plastics material.

The testing chemical may contain one or more of sulphuric acid, nitricacid or hydrochloric acid solution. In addition, the chemical may alsocontain a small quantity of a silver salt such as silver sulphate or asmall quantity of a chromate or dichromate such as sodium chromate.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described, by way of example, withreference to the accompanying drawing which is a longitudinalcross-section of an apparatus forming an embodiment of the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The apparatus 1 comprises a generally cylindrical plastics housing 3.The housing 3 is closed at one end 3a and partly open at the other end3b. Sealed within the housing is an insert comprising a reservoir 5containing a testing chemical and an applicator 7.

The reservoir 5 is a cut or moulded cylinder of uniform fibrous,granular or other porous plastic material such as polypropylene whichcan absorb and retain a testing chemical without deteriorating to anunacceptable extent. Other suitable materials for forming the reservoirare vinyl acetate, vinyl polymers, polyester, polyethylene,polyvinylidene fluoride and nylon, all in fibrous or granular form andformed or moulded with a suitable binding agent or glue.

The reservoir 5 is surrounded by a plastic or acetate film 9, to retainthe shape of the reservoir and prevent leakage of the testing chemical.The film 9, like the reservoir 5, must be resistant to the testingchemical so that it does not deteriorate to a great extent in use.Alternatively, the reservoir may be surrounded by a casing such as aglass or plastics tube.

The applicator 7 comprises a nib having a relatively narrow tapered wick7a at one end, which projects into the reservoir 5 and a wider tip 7b atthe other end which projects from the housing through its partly openend 3b. The outer surface of the tip 7b forms an applying surface 8 forapplying the testing chemical to an item to be tested. The wick 7a drawsup testing chemical from the reservoir 5 and transfers it to the tip.The applicator 7 is dimensioned and shaped to deliver a sufficientquantity of testing chemical to the tip, and thus to the item to betested, so that a reaction to the chemical is visible to the naked eye.

The applicator 7 is moulded from a fibrous, granular or other porousplastics material that is resistant to the testing chemical. Suitablematerials are the same as those used in the reservoir and includepolyvinylidene fluoride.

The following table illustrates examples of suitable materials for theapplicator and reservoir for different testing chemicals.

    ______________________________________                                        TESTING    MATERIAL OF    MATERIAL OF                                         CHEMICAL   RESERVOIR      APPLICATOR                                          ______________________________________                                        Dilute (e.g.0.5%-                                                                        Polypropylene, Polypropylene,                                      20%) sulphuric acid                                                                      polyethylene, polyester,                                                                     polyvinylidene fluoride                             solution containing                                                                      nylon, with or without                                                                       or any material of                                  a silver salt or a                                                                       coating        reservoir                                           chromate                                                                      Concentrated                                                                             Polypropylene, Polypropylene,                                      sulphuric acid                                                                           polyethylene, polyester,                                                                     polyvinylidene fluoride                             containing a silver                                                                      nylon, with or without                                                                       or any material of                                  salt       coating        reservoir                                           Dilute nitric acid                                                                       Polypropylene, Polypropylene,                                                 polyethylene, polyester,                                                                     polyvinylidene fluoride                                        nylon, with or without                                                                       or any material of                                             coating        reservoir                                           Concentrated nitric                                                                      Polypropylene, Polypropylene,                                      acid       polyethylene, polyester,                                                                     polyvinylidene fluoride                                        nylon, with or without                                                                       or any material of                                             coating        reservoir                                           Nitric acid                                                                              Polypropylene, Polypropylene,                                      containing a silver                                                                      polyethylene, polyester,                                                                     polyvinylidene fluoride                             salt or a chromate                                                                       nylon, with or without                                                                       or any material of                                             coating        reservoir                                           Hydrochloric acid                                                                        Polypropylene, Polypropylene,                                      concentrated or                                                                          polyethylene, polyester,                                                                     polyvinylidene fluoride                             dilute containing                                                                        nylon, with or without                                                                       or any material of                                  stannous chloride                                                                        coating        reservoir                                           Concentrated or                                                                          Polypropylene, Polypropylene,                                      dilute Hydrochloric                                                                      polyethylene, polyester,                                                                     polyvinylidene fluoride                             acid       nylon, with or without                                                                       or any material of                                             coating        reservoir                                           Aqua-Regia Polypropylene, Polypropylene,                                                 polyvinylidene fluoride                                                                      polyvinylidene fluoride                                        both with non-acetate                                                         coating and without any                                                       acid-dissolvable glues                                             ______________________________________                                    

Some of the above mentioned testing chemicals are colorless but some maycontain suitable dyes to improve the visibility of the reaction with theitem under test.

The apparatus has a cap 11 which covers the tip 7b when the apparatus isnot in use. On the closed end 3a of the housing, a "scratcher" 15 isprovided for testing jewels. In the embodiment, the scratcher 15 isformed from a small, industrial quality diamond, having a relativelyfine point which is used for scratching the surface of the jewel undertest. Alternatively, the scratcher 15 may be formed from diamond dust orgrit set in a hard wearing glue. The scratcher is used to scratch thesurface of the jewel under test and will mark the surface of jewelswhich are softer than diamond, such as cubic zirconia and other man madesimulents.

The scratcher 15 is mounted in a unique way to prevent the user fromapplying excess pressure to the jewel under test using the scratcher.This ensures that the scratcher does not mark a genuine diamond. Thescratcher 15 is thus mounted on an appropriately tensioned spring whichlimits the amount of pressure that can be applied by the user to thejewel under test. Thus, if the user attempts to apply pressure above apre-determined level, the spring will be compressed to reduce thepressure of the scratcher on the jewel under test, thus preventing itfrom being marked. Typically, the scratcher is mounted on a ball orother mounting which is in turn connected to the spring.

It will be appreciated that the scratcher could be made from relativelyhard jewels other than diamond, such as sapphire or ruby.

In an alternative embodiment the apparatus could include an electronicdiamond tester.

The apparatus in accordance with the invention is quick and easy to use.In addition, since the testing chemical is retained within a sealedreservoir which in turn is housed within a sealed housing, it is readilyportable without the risk of leakage and/or breakage. Furthermore, theapparatus automatically applies the appropriate quantity of testingchemical to the item being tested without spillage.

As the skilled person will appreciate, various modifications may be madeto the described embodiments. For example, the applicator may be formedof more than one material, for instance, the wick and inner part of thetip may be made from polypropylene and the tip may be covered by apolyvinylidene fluoride layer forming the applying surface. It isintended to include all such variations and modifications as fall withinthe scope of the accompanying claims.

What is claimed is:
 1. An apparatus for testing items of metalcomprising; a reservoir containing testing chemical, an applicator fortransferring testing chemical from the reservoir to an applying surfacethereof, a housing surrounding the reservoir and applicator with theapplying surface projecting therefrom, and in which the testing chemicalcomprises an acid selected from the group consisting of sulphuric acid,nitric acid and hydrochloric acid and a chemical selected from the groupconsisting of a silver salt, a chromate and a dichromate.
 2. Apparatusas claimed in claim 1, wherein the reservoir is surrounded by a materialwhich is resistant to deterioration by the testing chemical. 3.Apparatus as claimed in claim 1, wherein the applicator comprises a nibhaving a wick in contact with testing chemical within the reservoir. 4.Apparatus as claimed in claim 3, wherein the nib is formed of a materialwhich is resistant to deterioration by the testing chemical. 5.Apparatus as claimed in claim 4, wherein the nib is formed from amaterial selected form the group consisting of polyethylene,polypropylene and polyvinylidene fluoride.
 6. Apparatus as claimed inclaim 1, further comprising a hard jewel carried by the housing, thejewel being selected from the group consisting of diamonds, rubies andsapphires.
 7. Apparatus as claimed in claim 6, including means forresiliently mounting the hard jewel to the housing.
 8. Apparatus asclaimed in claim 7, in which the hard jewel is diamond grit which ismounted indirectly on a spring.
 9. Apparatus as claimed in claim 1,wherein the reservoir comprises a porous plastic material.
 10. Apparatusfor testing items of metal comprising; a reservoir containing a testingchemical, an applicator for transferring the testing chemical from thereservoir to an applying surface thereof, a housing surrounding thereservoir and applicator with the applying surface projecting therefrom,and a hard jewel carried by the housing and selected from the groupconsisting of diamonds, sapphires and rubies.
 11. Apparatus for testingitems of metal comprising: a reservoir containing testing chemical; anapplicator for transferring testing chemical from the reservoir to anapplying surface thereof, a housing surrounding the reservoir andapplicator with the applying surface projecting therefrom, and in whichthe testing chemical comprises stannous chloride and hydrochloric acid.12. Apparatus as claimed in claim 11, wherein the reservoir issurrounded by a material which is resistant to deterioration by thetesting chemical.
 13. Apparatus as claimed in claim 11, wherein theapplicator comprises a nib having a wick in contact with testingchemical within the reservoir.
 14. Apparatus as claimed in claim 13,wherein the nib is formed of a material which is resistant todeterioration by the testing chemical.
 15. Apparatus as claimed in claim14, wherein the nib is formed from a material selected form the groupconsisting of: polyethylene, polypropylene and polyvinylidene. 16.Apparatus as claimed in claim 11, wherein the reservoir comprises aporous plastic material.